Hydrocarbon compositions containing iodine as an antifriction agent



United States Patent Delaware No Drawing. Filed Jan. 31, 1962, Ser. No. 170,249 2 Claims. (Cl. 252-33) This invention relates to compositions containing iodine. In particular, it relates to such compositions which exhibit extremely low coelficients of friction.

There are many instances, particularly under boundary lubrication conditions where two rubbing surfaces to be lubricated are separated by a very thin film of lubricant. In these circumstances, it is desirable that there be very little friction occurring between the moving surfaces. To reduce this friction, it has been customary to fortify conventional lubricants with additives known as oiliness agents. It has now been discovered that very small quantities of iodine within a carrier medium act as an exceptionally effective oiliness agent. Moreover, this use of elemental iodine in such carrier mediums results in significant secondary benefits, that is, improvements in loadcarrying capacity and antiwear characteristics.

By oiliness agents is meant those materials which lower the coefficient of friction of certain materials, usually lubricants. Materials which prevent wear are known as antiwear agents. The two foregoing agents must be distinguished from additives which improve load-carrying capacity of lubricants. Such additives prevent the seizing and/ or welding of moving surfaces (usually metal parts) and are commonly referred to as extreme pressure or EP agents. These latter additives may sometimes prevent wear, but oiliness and EP properties are not generally found together to an equal degree in a given additive.

The instant invention relates to the discovery that much lower concentrations of iodine than those of any previously known oiliness agent, e.g., as low as 0.0001 wt. percent, of iodine in carrier mediums, e.g., hydrocarbons, can drastically lower the coefficient of friction existing between two rubbing surfaces which contact a carrier medium having iodine dispersed or dissolved therein. For example, as low as 0.00375 wt. percent of iodine in a mineral oil carrier medium can lower the coefficient of friction more than 50%. Suitable carrier mediums can be represented by hydrocarbons such as lubricating oils, organic liquids such as benzene, xylene, etc. In special circumstances, aqueous media, water, liquid emulsions and other fluid mediums such as air, inert gases and other gases can be used.

The hydrocarbons are the preferred carrier mediums. Preferably the hydrocarbons should not include highly reactive species. The preferred hydrocarbons are paraf fins, naphthenes and aromatics, with the paraffins and naphthenes most preferred, e.g., the compositions should contain at least 50% saturated hydrocarbons and at most 50% aromatics and not more than 20% of other unsatu- 3,184,409 Patented May 18, 1965 ness in certain uses can be improved in this property by adding iodine, e.g., solid products like paraflin wax, semisolid products like petrolatum and greases, or relatively non-viscous products like kerosene and gas oil or fuel oil. The preferred petroleum hydrocarbons are those boiling above 300 F. and especially preferred are those boiling above 500 F. at atmospheric pressure.

For many of the ordinary applications of the invention, lubricating oils, cutting oils, metal working oils, hydraulic fluids, pneumatic equipment oils, spindle oils, gear oils, and the like will be used as the carrier medium for the iodine. It is contemplated that the lubricating oils which are to be used as carrier mediums include straight mineral lubricating oils or distillates derived from paraffinic, naphthenic, asphaltic, or mixed base crudes or, if desired, various blended oils can be employed as well.

Of course, synthetic lubricating oils made from esters, polysiloxanes, carbonates, formals, polyglycols, and the like can also be used. Also mixtures of synthetic and mineral oils can be employed. However, there are other more specialized applications in which it is not necessary that conventional oil bases be utilized to carry iodine. Iodine crystals can be placed in sealed systems to provide lubrication as they gradually sublime. In this technique, the particular gas which happens to be in the sealed system provides a carrier medium. This latter application can be seen to be of particular significance for lubricating rocket or missile systems where the rubbing surfaces can be sealed and the circulating iodine will provide the neces sary lubrication.

Moreover, it has been discovered that the exposure of metal lubricating or rubbing surfaces to iodine results in a beneficial carryover effect. This means that the low frictional effect on rubbing surfaces will last for a time after that in which the surfaces are removed from the presence of iodine. Thus, the low frictional effects caused by the iodine can exert their protective effect even after the carrier medium containing iodine is removed from the system. The carryover effect can be of significant value in certain specialized applications. For instance, when rubbing surfaces are exposed to iodine, then at a later date in the absence of any lubricant, these same rubbing surfaces can be brought into rubbing contact with each other without causing excessive friction. This aspect of the invention can be particularly important when the weight of the lubricant is a critical factor. This weight factor is of great importance in a rocket missile system. For instance, in such a system a fluid carrier medium can be chosen without regard to its inherent lubrication values and only with regard to its coolant properties. Thus, a portion of the liquid fuel from the rocket and missile fuel system could be used as a carrier medium which obviously would not add extra weight to the system.

Aqueous solutions containing iodine or iodine complexes are effective metal working fluids or specialty lubricants (e.g., where nonflammability is desired). These solutions can be used in cutting, grinding, machinery, threading, tapping, wire drawing, extrusion, or any other metal working operation in which low friction, low tool wear, faster processing or better surface finish is desired. Since iodine is known to react with titanium, particularly at higher temperatures, these solutions are suitable for machining titanium as well as other metals and alloys normally considered difficult to work with.

iodine less soluble in water than in most organic sol- (2) Iodine in combination with inorganic iodides above solutions.

' faces.

vents. For example, at 25 (3., the solubility of iodine tions of iodine in water are hydrolyzed to a much smaller extent that those of other halogens. The equilibrium constant for the reaction:

is only about l0 at 25 C. An aqueous solution containing iodide, iodate, and free iodine or triodide ion, has a pH of just about 7.

' Suitable aqueous metal working solutions containing iodine are:

(1) Iodine alone dissolved in water.

such as KI dissolved in water.

(3) Complexes of iodine with polyhydric compounds dissolved in water. The polyhydric compounds would include starches, amylose, amylopectin, sorbitols, polyethylene glycols and any other compounds containing an appreciable number of OH groups. (Polyols are preferred to glycols.) I

.(4) Combinations of any of those listedabove.

Other additives can also be incorporated in anyof the These include corrosion inhibitors (e.g., nitrites, chromates, phosphates, imidazolines, sulfonates, amines), Wetting agents, thickeners and dyes. Mutual solvents such as alcohols or ethers can also be incorporated. r

For many practical applications conventional lubricating fluids, e.g., petroleum oils, hydrocarbons and organic fluids are the preferred carrier medium. In other applications fuels will be a preferred carried medium. In such carrier mediums, the overall final composition will desirably comprise a major proportion of fluid and 0.0001

to 0.99, preferably 0.001 to 0.90 of iodine by weight. All percentage concentrations referred to herein are by Weight and are based on the weight of the finished formulationv suitable primarily as concentrates, which in lubricatingv 7 service are diluted to lower concentrations, e.g., after the initial oiliness film has been established on the metal sur- Concentratio-ns between 0.0009% and 0.09% are particularly effective for providing oiliness while equilibrium conditions prevail. The most preferred concen trations are between 0.005 'and 0.085% by weight.

Inasmuch as iodine tends to be lost by sublimation from a lubricated metal surface, replacement of what is thus lost may be achieved by supplying iodine in extremely dilute solution, e.g., 0.0001 to 0.009%. 'In a particular example, the motor oil in the crankcase of an engine can In some instances when using iodine itself in a crankcase oil some loss of iodine by vaporization may occur, particularly at the higher oil temperatures. I-Iowever,

4 the incorporation of iodine into the fuel, rather than the lubricant, will circumvent this problem. Some dilution of the oil by the fuel always occurs and the fuel can be the source of iodine for the oil. With the relatively large amounts of fuel being utilized perv unit of time, the concentrations of iodine needed in the fuel can be very low.

Thus, friction and/ or wear, occurring in any fuel burning device (e.g., internal combustion engine, diesel engine, gas turbine) can be minimized or reduced by the incorporation of elemental diodine in the fuel. 1 The concentration range can be from.0.0001 wt. percent I to 0.9 wtpercent 1 although 0.0005 to 0.05 wt. percent I is preferred, all wt. percent being based on the weight of the final formulation. The fuels could consist of gasoline, heating oil, jet fuel, gas oil, kerosene ,or any other fuel in which iodine can be incorporated.

If necessaryor desirable, other additives could be used in combination with iodine in fuels for certain specific properties or to overcome any deficiencies (e.g.,.staining of metals). These would include sulfonates, unsaturated compounds, cyclic alcohols and the like.

Iodine can be incorporated in hydrocarbons or other liquid carrier mediums by either dissolving solid iodine in'the liquid, adding a solution .of iodine in a medium more volatile thanthe desired carrier medium and flashing off the more volatile substituent, or by bubbling iodine vapor through the desired carrier medium, e.g., a hydrocarbon.-

Other additives can be added to the carrier medium composition of the present invention in order to form a finished lubricant. Such additives include oxidation inhibitors such as phenothiazine or phenyl-wnaphthyh 1 amine; detergent inhibitors suchas the barium salt of isononyl phenol sulfide; pour point depressants such as copolymers ofvinyl acetate with fumaric acid esters of coconut oil alcohols; viscosity index improvers such as polymethacrylates; and the like.

The technique of the invention is applicable to all metals used in machines and including ferrous metals such as iron and steel, nonferrous metals such as aluminum, copper, silver, cadmium, and the like, and alloys such as bronze, constantan, and the like. Furthermore, the invention is applicable to nonnnetals such as glass and synthetic plastics. V v 7 It has been found that when iodine is used in the higher concentration ranges, i.e., from about 0.0075 wt. percent and above, e.g., 0.009 to 0.99 particularly between 0.09 and 0.99%, some staining occurs on certain metal parts, particularly iron and steel, that are in contact with the iodine. This stain has no effect on the oiliness and other "properties of the'iodine composition. However, it has been found that this staining can be'eliminated without affecting the otherwise desirable properties of the iodine. The elimination of such staining constitutes an additional feature of the invention. 7

Elemental iodine atoms or molecules in unreacted form in solution can form a loose associationwith other materials to form a complex. Many complexes of iodine exist. The well-known complexes; include those of iodine with benzenes, ketones and ethers. Iodine also forms complexes with starch, polyhydric compounds and compounds containing a carbonyl group, as .WCll as with nitrogen-containing compounds. Theseiodine complexes are useful as additives to reduce friction and wear. Ma-

te'rials with Which iodine forms complexes useful as additives include the following specific examples:

Nitrogen containing compounds such as vpyridines, picolinesjquinolines, isoquinoline, quinaldine, indole, acridine, acridone, c'arbazoles, piperazines and the like;

Ethers such as di-n-amyl ether, divinyl ether, diphenyl ether, 'anisole, dibutyl Carbitol, 2-methyl-2-ethyl-1,3- dioxolane, 2,3-epoxy-2-ethyl hexanol, styrene oxide, tri- Qisobutylene' oxide, epichlorohydrin and dipentane dioxide andthe like; p, i i A Alcoholssuch. as hexanol, isooctyl alcohol, tridecyl alcohol, hexadecyl alcohol, eicosyl alcohol, cyclohexanol, n-decyl alcohol and benzyl alcohol and the like;

Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl butyl ketone, isophorone, isobutyl .heptyl ketone, stearone, mesityl oxide, cyclohexanone and benzophenone, and the like;

Acids such as formic, acetic, caprylic iodoacetic, glycolic, lactic, thioglycolic, cyanoacetic, 2-ethyl hexoic, isodecanoic, naphthenic, benzoic, oleic, ricinoleic, 0x0 acids and C dimer acids, and the like;

Esters such as isopropyl acetate, vinyl acetate, butyl Cellosolve acetate, sebacates, adipates, silicates, succinates, oleates, carbonates, and the like;

Aldehydes such as n-heptaldehyde, C -C C Oxo aldehydes, stearaldehyde, Z-methylpentaldehyde, 1,2,3,6 tetrahydrobenzaldehyde, and furfural, and the like.

Polymers having the above functional groups or combinations thereof are also suitable. Sulfonic acids and their salts are also suitable. Iodine can be mixed in suitable proportions, e.g., equimolar, with compounds of those classes and the mixtures can be dissolved in hydrocarbons. Alternately iodine and one or more compounds of those classes can be dissolved separately in the same hydrocarbon. The resulting hydrocarbon solutions of the iodine complexes retain the properties of lowering the coefficient of friction and decreasing or preventing the wear of metal surfaces in machines but said solutions do not stain said metal surfaces. For instance, in illustration of the above, the following specific compounds in the presence of the iodine will eliminate stain ing. These compounds as examples are a mixed 1,2 epoxyhexadecane and 1,2 epoxyoctadecane obtainable commercially as a G -C olefin oxide from the FMC Corp, barium sulfonate, and decyl alcohol. The above compounds are used in amounts of 50-150, e.g., 75-100, wt. percent based on the Weight percent of iodine.

The use of sulfonates in connection with the iodine not only eliminates staining but also permits the attainment of good high temperature lubrication characteristics. For some types of lubrication the bulk temperature of the lubricant can reach such high temperatures so as to cause the iodine to be driven out of the carrier medium. For example, by using barium sulfonate in conjunction with iodine, adequate retention of the excellent lubri eating properties of the iodine alone is accomplished. Although barium sulfonate is a preferred sulfonate other detergent additives can be used. The detergent lubricant additives which are preferred and are well known in the lubricating art include the petroleum sulfonates, synthetic alkyl aryl sulfonates, various alkyl phenates, alkyl phenate sulfides, phosphosulfurized olefin polymers, and various combinations of these additives. Following are specific descriptions of several of the above types of detergent additives.

Petroleum sulfonates generally used as lubricating oil detergents are the oil-soluble alkaline earth metal salts of high molecular Weight sulfonic acids. These sulfonic acids are produced by the treatment of petroleum oils of the lubricating oil range with fuming sulfuric acid and generally have molecular weights of about 300 to 700, e.g,. 350 to 500. Petroleum sulfonates are well known in the art and have been described in numerous patents, e.g., US. 2,467,176.

Detergent sulfonates can also be derived synthetically from relatively pure alkyl aryl sulfonic acids having from about to 33 carbon atoms per molecule. For example, sulfonated products of alkylated aromatics such as benzene, toluene, xylene, and naphthalene, alkylated with olefins or olefin polymers of the type of polypropylene, polyisobutylene, etc. can be used.

Specific examples of the above two types of sulfonates include calcium petroleum sulfonate, barium petroleum sulfonate, calcium di-C alkyl benzene sulfonate, barium di-C alkyl benzene sulfonate and calcium C alkyl benzene sulfonate; wherein said (ii-C alkyl group is derived blend.

from diisobutylene; said C alkyl group is obtained from tripropylene and said C alkyl group is obtained from tetraisobutylene.

The above sulfonates may be either neutral sulfonates, i.e., where the sulfonic acid is neutralized with an equal mole equivalent amount of metal base, or the sulfonates may be of the so-called high alkalinity type. In the latter case, additional metal base, in excess of that required for simple neutralization, is reacted with the sulfonate sulfonic acid to form an alkaline product which can then be blown with carbon dioxide to reduce its alkalinity and form a substantially neutral final product. Recent work has indicated that such so-called high alkalinity sulfonates are probably dispersions of neutral sulfonates and a carbonate of the metal used which are believed to exist in the form of colloidal sols. In any event, the term sulfonate as used herein and in the appended claims includes both neutral sulfonates and socalled high alkalinity (or high metal content) sulfonates.

The invention will be further understood by reference to the following examples which illustrate preferred forms of the invention. All percentages of the compositions of the examples are weight percentages and based on the weight of the finished composition.

Example I In order to evaluate the compositions of the examples, they were tested in a rotating cylinder apparatus designed to measure metallic contact and friction between sliding, lubricated surfaces. Other noninventive compositions were also evaluated for comparison purposes. A complete description of this apparatus was given in a paper entitled, Metallic Contact and Friction Between Sliding Surfaces by M. J. Furey presented at the 1960 Joint ASLE-ASME Lubrication Conference, October 19, 1960, in Boston, Mass. This paper has been published by the American Society of Lubrication Engineers, 5 N. Wabash Ave., Chicago 2, Illinois, under the above noted title in ASLE Transactions, volume 4, Number 1, pages 1-11, April 1961. The apparatus has also been described in copending application S.N. 80,474, filed January 3, 1961, now US. Patent No. 3,129,580, by M. I. Furey and I. A. Wilson. The paper and copending application are herewith incorporated in their entirety in this application.

The apparatus consists basically of a fixed metal ball loaded against a rotating steel cylinder. The extent of metallic contact is determined by measuring both the instantaneous and average electrical resistance between the two surfaces. It is expressed as the percent of the time that metallic contact occurs in a given period of time. Friction between the ball and cylinder is recorded simultaneously with contact. This is noted as coefficient of friction which is the ratio of friction force to the load. It has been found that there is, in general, a good correlation between metallic contact measured in this manner and the amount of surface damage which occurs.

The evaluations of the compositions were obtained under the following conditions unless otherwise noted:

System: AISI 52100 Steel, /2" diam. ball on 1%" diam.

cylinder Load: 240 grams (54,700 psi. mean Hertz pressure) Speed: 240 r.p.m. (56 cm./sec. sliding velocity) Time: 32 minutes Temperature: 77 F.

A solution containing 0.75 wt. percent iodine was prepared by adding elemental iodine to a solvent-extracted, paraflinic, neutral mineral oil having a viscosity of SUS at 100 F. and mixing at ambient temperature. The resultant blend was clear with a dark amber color. A portion of this blend was set aside and the remainder diluted to give a blend having a 0.075 wt. percent concentration of iodine. The latter blend was further diluted in the same manner and treated identically as the first This procedure was carried out until there were five blends containing the concentrations of 0.75

'iodine or other additivesawas used as a control.

. Table 1 a a 1 EFFECT OF IODINE ON METALLIC CONTACT AN V FRICTION Base oil: Mineral oil (100 sus at 100 F.) Time: 32 minutes V Table 2 V EFFECT OF IODINE ON METALLIC CONTACT AND FRICTION Base oil: White oil (100 SUS at 100 F.) Time: 32 minutes Concentration Percent Coefliclent Blend a of iodine metallic of friction 7 (wt. percent) contact Concentration Average per- Average Blend of iodine cent metallic coefiicicnt I (wt. percent) contactv ofiriction As can be seenby the. above data from Table 1, the:

EXAMPLE II It is well known that solutions of iodine generally fall The, average reduc- For example, the V contact and friction.

As can be seen by the above Table 2, the results obtained with iodine in a white 'oil are quite outstanding. On the average, iodine reduces metallic contact and friction by about 95% and 85% respectively in these tests.

EXAMPLE III In order to determine the effectiveness of various additives in preventing metal staining by the iodine, a series of four blends was prepared. One blend was the base oil of Example I; one blend was the same base oil plus 0.85 wt. percent iodine and the other two blends were the base oil plus 0.85 wt. percent iodine plus 1 wt. percent each of a series of additional additives. The question to be determined was whether or not these compounds could reduce staining and, if they reduced staining, would they have any adverse effect, on the ability of iodine to reduce The. blends, as described above, were labeled N through S. Each test piece was then immersed in cc. of the oil blend for 72 hours at room temperature. In this test, the test ball was an AISI 52100 steel /2 inch test ball and the time of testing was 72 hours at room temperature. The results of the test and the designation of the blends are summarized below in Table 3.

Table 3 EFFECT OF IO DINE AND OTHER ADDITIVES ON STAINING, METALLIC CONTACT AND FRICTION Base oil: Neutral mineral oil (100 SUS at 100 F.)

into two main. classes, amber and violet. In Example I above it was observed that the blends .of iodine in the 100 SUS mineral oil were various shades of amber. It had been observed that when iodine blends were prepared in white oil, the blends had a violet color. Therefore, to determine whether the form in whichthe iodine was present had any influence on metallic contact and coeflicient of friction, ball-on-cylinder tests were carried out with blends of'iodine in a White oil which was a-high 1y refined mineral oil. This white oil had a yiscosity of of 100 SUS at 100 Band is obtainable commercially as Marcol JX from the Humble Oil & Refining Co. The method of preparation. and evaluation was similar to that described in Example I. White oil alone without The As can be seen by the above table, the additives in the iodine blend completely eliminated dark stain.

The barium sulfonate used in the above test was Hybase barium sulfonate obtained from Bryton Company and prepared by the carbonation process previously described.

Thus, the inclusion of iodine in a carrier medium such as a lubricating oil results in a. reduction of metallic contact and a lowering ofthe coefiicient of friction far beyond blends were labeled from G through M. The results (aver- 1 7 age) of they tests and the designations of the blends are summarized below Table that obtainable'with ordinary additives. 'For instance,'a

typically eifective material of the prior art for reducing friction. under conditionssimilar to those of the above examples. was one weight percent of isopropyl oleate. It reduced friction by about 50%. Moreover, other conventional antiwearadditives such as oleic acid, tricresyl phos- 9 EXAMPLE IV In order to evaluate the iodine-containing compositions with similar compositions containing other halogens, e.g., gromine, the following. procedure was carried out. Blends D, E, and F were compared in the ball-on-cylinder apparatus with three identical blends except that bromine was used in place of iodine. Blend A was used as the base oil. It is to be noted that in performing these tests in this and other examples, a new ball is used with each new portion of the cylinder. Thus, a new ball and fresh cylinder track was used for each run with a given additive. For a given additive, tests were started with the base oil, then the lowest concentration, and so onusing one cylinder. Dilferent additives were tested on different cylinders, however. All the I data below were obtained on one cylinder and all the Br data were obtained on another. (A new ball and fresh track were used for each test.) This accounts for the variations in test results wherein the figures for metallic contact and coefiicient of friction vary with respect to the same base oil. The results of the evaluation are summarized in Table 4 below.

lower, especially preferred, concentrations of the present invention the load carrying capacity is not very significant. Therefore, at the preferred concentrations of the invention, load carrying properties are minimal but the property of decreasing the coefficient of friction is at a maximum.

EXAMPLE VI Table 6 EFFECT OF IODINE ON WEAR WITH STEEL AT HIGHER LOADS Balkan-cylinder tests AISI 52100 Steel (nnhardened) Base oil: white oil Time: 32 minutes Speed: 240 r.p.n1.

L d( I n dwemtscar a ams q 111 O lame er 011 Table 4 gr ball (mm Percent metallic Coefficient of 0. 48 friction 0.26 0.78 8'33 H l I B 1 13 a ogen 2 1'2 2 In 0' 48 Wt. percent in neutral lube oil having a vis. of100 SUS 1 0.075% by weight. at 100 F.:

$2 8- gggg The above data show that a 0.075 wt. percent blend 1 100 01020 01090 of iodine in white oil decreases wear over a range of loads between 240 and 4000 grams by about 50% regard- The above table demonstrates that iodine decreases metallic contact and coeflicient of friction to a much greater extent than bromine under identical conditions.

EXAMPLE V In order to evaluate the compositions of the invention, Blends D, E, and F, and I, J, and K were tested in an S.A.E. machine and a shell 4-ball E.P. test. These are well-known tests in the lubricating art.

The results of these tests are summarized in Table 5 which follows.

Table 5 EXTREME PRESSURE PROPERTIES OF MINERAL OILS CONTAINING IODINE S.A.E. ma- 4-ball El. test chine load carrying Lubricant capacity Seize Weld lbs. point point Neutral solvent extracted distillate 100 63 100 +0.0075% 100 56 100 +0.076% 100 100 141 +0.75% I 4, 000 178 355 White oi1 100 36 89 +0 00 100 45 100 0.0757 I2 2, 600 112 178 +0.75 3, 800 141 355 1 Failed in less than 5 seconds during break-in. 2 Test discontinued at this lead with no welding.

The above tests demonstrate that iodine in concentrations as high as 0.5 wt. percent begins to show some load carrying capacity. This would be expected from the prior art teachings on halogens in general. However, in the less of the load.

EXAMPLE VII Blend 1' was again evaluated in the ball-on-cylinder test at 240 r.p.m. and at a 240-gram load except that the metals contacting each other varied. In the first test, the metals contacting each other were steel-on-steel. In the second test, they were bronze-on-steel. In the third test they were silver-on-steel; in the fourth, constantanon-steel. The results of these tests are summarized below in Table 7.

Table 7 EFFECT OF IODINE 0N WEAR WITH VARIOUS METAL- ON-SIEEL SYSTEMS Base oil: White oil Ball-on-cylinder tests at 2 10 r.p.m. and 240 g. load Time: 32 minutes actual reduction varying from about 24% (silver-onsteel) to 69% (constantan-on-steel). This demonstrates that the type of metals contacting each other is relatively unimportant. Thus, excellent results are obtained when different metals contact each other.

Table 8 EFFECT OF IODINE ON LUBRICATION OF ALUMINUM-ON-ALUMINUM V Base oil: White oil 7 Ball-on-cylinder-tests at 240r.p.m. Time: 32 minutes 7 V V Percentv Coeflicient Wear 1 Load (gins) metallic of friction scar contact 3 1 0.075% by weight. 7 2 Scufliug and chattering occurred during this test (excessive bouncing probably explains 48% metallic contact).

The above data demonstrate that the compositions of the invention providea low coefficient of friction and low wear in an aluminum -on-aluminum system. i

j EXAMPLE, VIII SUS and with a commercial type motor oil having a 40 viscosity of 12.4 centistokes at 210 B, Other test'conditions of this engine were a brake hp. of- 52, a wate'r jacket temperature of 180 F.i3,and anair intake ternperature of 110 13:5. The engine wasplaced on a 5 dynamometer-test stand and the torque that was reg iired to operate it was both measured and [recorded with a strain gauge system. The system was so equippedthat' at any time during the running of the engine the friction could be measured. The system also was equipped with a measured sight glass containing fuel which could be used to determine the fuel consumption of the engine during its operation. The technique employed in this test isfully described in a paper entitled, The Efiect of Lubricant Viscosity and Composition on Engine Friction and Bearing Wear by E. H. Olrrent which was published in the ASLE Transactions, volume 4, Number 1, April 1961. The specific details of this technique are given on page 98 of this publication. The results of this test are summarized below in Table. 9.

thenate, and oleic acid.

1 pert.

Table 9 EFFECT OF IODINE ON ENGINE FRICTION Percent improvement Frictional in fuel consumption 11.1. over test with regular motor oil 1 Regular motor oil (12.4 (as/210. F.). 25. 0 0 Neutral lube oil (4.2 cs./210 F.) 24. 0 1. 3 Neutral lube oil +0.75% In after operation for:

' 1 Based on indicated 11.1. which is the sum of the friction H.P. and brake 11.1. (in this case 52). p

.The above data show that approximately 51.12% reduction in-friction'al'HI. in a Chevrolet V-8 engine as well as a 5% reduction in fuel consumption as compared with 'a regular motor oil .was attained with 0.75% iodine dissolved in'the oil. With the mineral oils alone, the friction H.P. remains constant withtime.

While the above invention has beendescribed with some'particularity, it is to be understood that minor modifications can be made while-still retaining the spirit and scope of the invention as hereinafter claimed.

What is claimed is:

1. A lubricating oil composition comprising a major proportion of a minerallubricating oil and a frictionreducing amount, within the range of 0.0009 to 0.09 Wt. percent, of iodine. W

2. A composition according to claim 1, in which said iodine has a tendency to stain iron, and a material complexed with said iodine having the ability to reduce said tendency to stain, said material being selected from the group consisting .of barium sulfonate, cadmium naph- References Cited by the Examiner UNITEDVSTATES PATENTS 2,771,348 11/57' Meguerianl 44--79X 3,115,467 12/63 Denison'et a1. 252 ss FOREIGN PATENTS 1*,252' 6/55v Great Britain., 5,256 10/97 Great Britain. 503,313 4/39 7 Great Britain.

p 1 1 .OTHER REFERENCES Daveyz .The Extreme Pressure (E.P.) Lubricating Properties of Some Bromine and Iodine Compounds, etc., I. Inst. PetroL; 33, 673 (1947), pp. 673-677 pertinent.

. Forbesz fLubrication of Industrial and Marine MachineryfWiley & Sons, Inc., 1943, pp. 231-235, 250-256 Peterson et a1.: Factors Influencing Friction andWear With Solid Lubrican Lubrication Eng., September- October 1955, pp. 325-330 pertinent.

DANIEL E. WYMAN, Primary Examiner. 

1. A LUBRICATING OIL COMPOSITION COMPRISING A MAJOR PROPORTION OF A MINERAL LUBRICATING OIL AND A FRICTIONREDUCING AMOUNT, WITHIN THE RANGE OF 0.0009 TO 0.09 WT. PERCENT, OF IODINE.
 2. A COMPOSITION ACCORDING TO CLAIM 1, IN WHICH SAID IODINE HAS A TENDENCY TO STAIN IRON, AND A MATERIAL COMPLEXED WITH SAID IODINE HAVING THE ABILITY TO REDUCE SAID TENDENCY TO STAIN, SAID MATERIAL BEING SELECTED FROM THE GROUP CONSISTING OF BARIUM SULFONATE, CADMIUM NAPHTHENATE, AND OLEIC ACID. 